1. Field of the Invention
This invention pertains generally to circuit interrupters and, more particularly, to circuit breakers including a latchable cradle and a cross bar adapted to move in an arcuate path and, more particularly, to such circuit breakers including primary and secondary latches.
2. Background Information
Circuit interrupters, such as circuit breakers, are employed in diverse capacities in power distribution systems. A circuit breaker may include, for example, a line conductor, a load conductor, a fixed contact and a movable contact, with the movable contact being movable into and out of electrically conductive engagement with the fixed contact to switch the circuit breaker between an on or closed position and an off or open position, or between the on or closed position and a tripped or tripped off position. The fixed contact is electrically conductively engaged with one of the line and load conductors, and the movable contact is electrically conductively engaged with the other of the line and load conductors.
Circuit breakers may also include an operating mechanism having a movable contact arm upon which the movable contact is disposed, a pair of links, a main spring, a latch mechanism, a cradle and a movable operating handle that extends outside of a housing for the circuit breaker. The cradle is pivotally disposed between the latch mechanism and the links. One portion of the cradle pivots with respect to the housing while another portion of the cradle has a latch ledge, which is latched by the latch mechanism.
It is known to employ latch mechanisms including a primary latch and a secondary latch. See, for example, U.S. Pat. Nos. 6,747,534 and 6,140,897.
It is also known to employ primary and secondary latches in a multi-pole circuit breaker including a pivotal linkage between the poles thereof. The primary latch is disposed above the secondary latch which is above the pivotal linkage.
It is further known to employ a multi-pole circuit breaker including a cross bar between the poles thereof. The cross bar moves in an arcuate path between a first position wherein the separable contacts of the poles are open or tripped open, and a second position wherein such separable contacts are closed.
It is very desirable to have a consistent interface between the cradle and the primary latch in the circuit breaker operating mechanism.
One obstacle to a consistent interface is the use of welded or joined cradles. These multi-piece assemblies are needed to provide both consistent position of the cradle relative to the side plates and a strong, centrally located interface with the primary latch. The requisite bends and joins make the exact position of the cradle latch interface problematic.
There is room for improvement in circuit breakers including a latchable cradle and a cross bar adapted to move in an arcuate path away from primary and secondary latches.